Periodograms of the TIGRE τ Boo time series; the dotted line shows the periodogram of the LS analysis for the data until 2463 [HJD-2 455 000], the solid and color-coded lines show the periodograms of the LS analysis for the seasonal data with the coding scheme as used in Fig. 1. Furthermore, the formal 7σ limit for the data until 2463 [HJD-2 455 000] is shown as a dash-dotted line and the mean 3σ limit of the seasonal data as a dash-triple-dotted line.